docs: add details fuel types

docs/docs/about/references/keywords/FUEL_TYPES.md

@@ -1,8 +1,13 @@
 # FUEL_TYPES
+:::note
+The [FUEL_TYPES](/about/references/keywords/FUEL_TYPES.md) keyword is **mandatory** within the eCalc™ YAML file.
+:::
 
 [FUEL_TYPES](/about/references/keywords/FUEL_TYPES.md)
 
 ## Description
+`FUEL_TYPES` is one of six top level section keywords in eCalc™.
+
 This part of the setup specifies the various fuel types and associated emissions
 used in the model. Each fuel type is specified in a list and the defined fuels can later be referred to the 
 [INSTALLATIONS](/about/references/keywords/INSTALLATIONS.md) part of the setup by its name.

docs/docs/about/references/keywords_tree/FACILITY_INPUTS/TYPE/index.md

@@ -13,10 +13,11 @@ Facility input type. The supported types are:
 - [ELECTRICITY2FUEL](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/ELECTRICITY2FUEL.md)
 - [TABULAR](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/TABULAR.md)
 - [COMPRESSOR_TABULAR](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/COMPRESSOR_TABULAR.md)
-- [PUMP_CHART_SINGLE_SPEED]
-- [PUMP_CHART_VARIABLE_SPEED]
+- [PUMP_CHART_SINGLE_SPEED](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/PUMP_CHART_SINGLE_SPEED.md)
+- [PUMP_CHART_VARIABLE_SPEED](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/PUMP_CHART_VARIABLE_SPEED.md)
 
-The documentation of each of these is found on the [Facility Inputs](/about/modelling/setup/facility_inputs/index.md) page.
+The documentation of each of these is found under [TYPE](/about/references/keywords_tree/FACILITY_INPUTS/TYPE/index.md) 
+and on the [Facility Inputs](/about/modelling/setup/facility_inputs/index.md) page.
 
 ### Format
 

docs/docs/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/FACTOR.md

@@ -0,0 +1,23 @@
+---
+sidebar_position: 2
+---
+# FACTOR
+
+[FUEL_TYPES](/about/references/keywords_tree/FUEL_TYPES/index.md) /
+[EMISSIONS](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/index.md) /
+[FACTOR](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/FACTOR.md)
+
+## Description
+`FACTOR` is a single value (kg/Sm<sup>3</sup>) used to define the emissions in kg per Sm<sup>3</sup>
+of the fuel gas used on the installation. That is, how many kilograms of e.g. CO<sub>2</sub> are emitted per 
+Sm<sup>3</sup> of fuel gas burnt.
+
+Say your fuel emits 2.5 kg CO<sub>2</sub> per Sm<sup>3</sup> of burned fuel, you can model this like
+
+~~~~~~~~yaml
+FUEL_TYPES:
+  - NAME: my_fuel
+    EMISSIONS:
+      - NAME: CO2
+        FACTOR: 2.5  # [kg/Sm3]
+~~~~~~~~

docs/docs/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/NAME.md

@@ -0,0 +1,26 @@
+---
+sidebar_position: 1
+---
+# NAME
+
+[FUEL_TYPES](/about/references/keywords_tree/FUEL_TYPES/index.md) /
+[EMISSIONS](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/index.md) /
+[NAME](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/NAME.md)
+
+## Description
+Emission name.
+
+### Format
+~~~~~~~~yaml
+EMISSIONS:
+  - NAME: <name of emission>
+    ...
+~~~~~~~~
+
+### Example
+
+~~~~~~~~yaml
+EMISSIONS:
+  - NAME: CO2
+    ...
+~~~~~~~~

docs/docs/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/index.md

@@ -0,0 +1,38 @@
+---
+sidebar_position: 2
+---
+# EMISSIONS
+
+[FUEL_TYPES](/about/references/keywords_tree/FUEL_TYPES/index.md) / 
+[EMISSIONS](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/index.md)
+
+
+
+| Required   | Child of                  | Children/Options                   |
+|------------|---------------------------|------------------------------------|
+| No         | `FUEL_TYPES`         | `FACTOR`  <br />  `NAME`            |
+
+
+## Description
+In [EMISSIONS](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/index.md) one or more emissions related to the use of fuel is specified as
+a list. Each emission entry is **required** to have a [NAME](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/NAME.md) 
+and a [FACTOR](/about/references/keywords_tree/FUEL_TYPES/EMISSIONS/FACTOR.md).
+
+
+## Format
+~~~~~~~~yaml
+EMISSIONS:
+  - NAME: <name>
+    FACTOR: <factor>
+~~~~~~~~
+
+## Example
+For example, if you want to add CO<sub>2</sub> emissions associated to the usage of a [FUEL_TYPES](/about/references/keywords_tree/FUEL_TYPES/index.md)
+you write the following:
+
+~~~~~~~~yaml
+EMISSIONS:
+  - NAME: CO2
+    FACTOR: 2.5  # [kg/Sm3]
+~~~~~~~~
+

docs/docs/about/references/keywords_tree/FUEL_TYPES/NAME.md

@@ -0,0 +1,25 @@
+---
+sidebar_position: 1
+---
+# NAME
+
+[FUEL_TYPES](/about/references/keywords_tree/FUEL_TYPES/index.md) /
+[NAME](/about/references/keywords_tree/FUEL_TYPES/NAME.md)
+
+## Description
+Fuel type name.
+
+### Format
+~~~~~~~~yaml
+FUEL_TYPES:
+  - NAME: <name of fuel, for reference>
+    ...
+~~~~~~~~
+
+### Example
+
+~~~~~~~~yaml
+FUEL_TYPES:
+  - NAME: some_fuel_name
+    ...
+~~~~~~~~

docs/docs/about/references/keywords_tree/FUEL_TYPES/index.md

@@ -13,4 +13,9 @@ used in the model. Each fuel type is specified in a list and the defined fuels c
 The use of fuel can lead to one or more emission types, specified in [EMISSIONS](/about/references/keywords/EMISSIONS.md).
 You can optionally specify a [CATEGORY](/about/references/keywords/CATEGORY.md).
 
+This part of the setup specifies the various fuel types and associated emissions
+used in the model. Each fuel type is specified in a list and the defined fuels can later be referred to the 
+[INSTALLATIONS](/about/modelling/setup/installations/index.md) part of the setup by its name.
+
+
 See [FUEL TYPES](/about/modelling/setup/fuel_types.md) for more details about usage.

docs/docs/about/references/keywords_tree/MODELS/index.md

@@ -6,6 +6,8 @@ sidebar_position: 4
 [MODELS](/about/references/keywords_tree/MODELS/index.md)
 
 ## Description
+`MODELS` is one of six top level section keywords in eCalc™.
+
 Each element is specified in a list. These are later used as input to other models, or in the
 [INSTALLATIONS](/about/references/keywords_tree/INSTALLATIONS/index.md) part of the setup by referencing their
 [NAME](/about/references/keywords_tree/MODELS/NAME.md).